Plugboard assembly



PLUGBOARD ASSEMBLY 4 Sheets-Sheet 1 Dec. 24, 1968 c. E. CAMPBELL, JR

Filed April 20. 1966v 041,0, 'l'a'a K0II000001, H3000 0000 [W0000000000A l 000000000 000000000 W0000000 0001 0001i 00000000000000 00000000/) .|000l00000 ,000 0010 0 0 000 |0v0l00000000 0000 0 00I0 .00000000000000 000000000000 0000100 \|\I| II/0l00ll00 ,0" 'l adlppdp 0A00000005J 000000000 INVENTOR. CLAYTON E. CAMPBELLJR. HIM/L Faas FIG. 4

c. E. CAMPBELL, JR 3,418,621

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PLUGBOARD AS SEMBLY 4 Sheets-Sheet 2 Filed April 20, 1966 mvENToR.CLAYTON E. CAMPBELL JR.

BY 2 f 54' Dec- 1?-4,v 1968 c. E. CAMPBELL, JR 3,418,621

PLUGBOARD ASSEMBLY Filed April 20, 1966 4 Sheets-Sheet :s

INVENTOR. Fl 9 CLAYTON E. CAMPBELL JR. Y

BY 2 L c. E. CAMPBELL, .1R 3,418,621

PLUGBOARD AS SEMBLY 4 Sheets-Sheet 4 Filed April 20, 1966 FIG. I

INVENTOR. CLAYTON ECAMPBELL JR.

BY j

III

www HW WH ,I i l United States Patent C 1 3,418,621 PLUGBOARD ASSEMBLYClayton E. Campbell, Jr., Greensboro, N.C., assignor to Cam Corporation,Greensboro, N.C., a corporation of North Carolina Filed Apr. 20, 1966,Ser. No. 543,902 12 Claims. (Cl. 339-18) ABSTRACT F THE DISCLOSURE Apatchcord system which is utilized in :connection with electricalaccounting machines, computers and the like, having front and rear bayscarrying plugwires and mating contact springs, the bays pivotallyconnected for cooperative electrical connection between the plugwiresand springs. A cam is employed to insure reliable electricalconductivity between the plugwires and the springs, and the system maybe shielded alternatively by a novel shielding means if desired.

It has become the prevailing practice to provide in electricalaccounting machines, computers and the like, a fixed panel on which arearranged a group of electrical contacts in rows and columns, certain ofthese contacts being connected to the sensing elements of the machine ormechanism and the remainder providing terminals for the leads connectedto the instrument panels that perform the operative functions of themachine. A control or movable panel is also provided which cooperateswith the fixed panel to furnish circuit connections between the contactsassociated with the sensing elements and the instrumentalities desiredto be operated according to some predetermined arrangement.Conventionally, the control or movable panel is adapted to be detachedfrom the assembly for the purpose of interchanging such panels whenevera variation of circuit connections or arrangements is desired, it beingcommon practice to provide a pre-set control panel for each of thecircuit arrangements periodically desired to be set into the machinewhereby a particular group of computations may be similarly handled in`accordance with certain standard reports to be rendered by the machine.

It has been found the desired mode of system construction to support thecontrol panel within a frame which may be pivotally connected to thefixed panel, the pivotal displacement of the frame juxtaposing thepanels into a parallel and operative relationship. To distribute evenlythe contact pressure throughout the assembly whereby warping of thecontrol panel is prevented, it is preferable that the panels, orplugboards, first be brought to a parallel position with the two sets ofcontacts being in an overlapping equally spaced relationship. Subsequentmovement of the movable panel parallel to and along the fixed panelcauses the contacts to engage simultaneously with an even distributionof pressure.

To render such a plugboard assembly practical, good electrical contactbetween the panels must be insured. It

has been found, however, that merely bringing the cony trol panel plugsinto direct engagement with the fixed lpanel terminals or numbers doesnot result in good electrical contact because, among other reasons, theaccumulation of dust and films on the contacts induces corrosion andpitting of the contact surfaces when these are not abraded in someconsistent and effective manner.

In a conventional plugboard assembly or system, up to several hundredcontact elements can be located on each board in a minimum area with aminimum spacing between rows and columns. As a result, where the boardis formed from an insulating material, current leakage can occur betweencontacts producing a more or less 3,418,621 Patented Dec. 24, 1968 ICCdetrimental effect on the operation of the machine according to itscharacter. For example, in an analog computer, information is generallyrepresented by voltage pulses or levels which are compared forresolution to a fixed reference level on the basis of relativemagnitude. Any significant leakage between contacts on the plugboard atthe control station introduces an error function in the transferral ofinformation which should be avoided. This current leakage, in contactboards as heretofore designed, may appear either as volume leakagethrough the body of the insulating or plastic material, or as surfaceleakage between the contacts and becomes a more significant factorshould there be flaws or imperfections within the composite structure ofthe board or an accumulation of film or foregin matter on the surfacesof the board.

A solution is to shield the contacts in the plugboard assembly againstcurrent leakage by forming the boards of a conductive material andproviding insulation sleeves for the Contact elements with boardapertures. As a matter of practice, it has been found practicable anddesirable to use a composition non-conductive material in theconstruction of the movable or control panels and then provide thesepanels with a cotaing of conductive material so as to insure a positiveground of the front panel and all conductive connections to that panel.Additionally, to isolate the individual connections between controlpanel plugwires and spring contact members held by the rear panel,interlaced strips of conductive material forming a grid having aplurality of individual compartments have been used and secured to therear panel of plugboard assemblies to avoid erroneous or faultyinformation transferral because of current leakage on noninsulated ornonshielded assemblies.

Accordingly, it is an object of the present invention to provide in acontact assembly for plugboards and their components a spring contactwhich assures Ia clean positive electrical contact.

Another object of the present invention is to provide a contact assemblyfor plugboards wherein the relative movement of the contact carriers isdirectionally translated into a wiping action between the contacts.

A further object of the present invention is to provide in a plugboardassembly a spring Contact member to engage a mating plugwire which issimple to insert Vand lock in position in the associated contactcarrier.

Still another object of the present invention is to provide in aplugboard assembly a spring contact of a durable single piececonstruction and simple design.

Still another object of the present invention is to provide in aplugboard assembly an improved shielded contact board composition andconstruction.

Yet another object of the present invention is to provide a plugboardassembly that, when closed and reopened, will automatically cleancontact surfaces to insure positive engagement and electricalconduction.

Yet a further object of the present invention is to provide in aplugboard assembly a spring contact and associated or mating plugwirethat results in a positive electri- Acal connection for associatedequipment.

Yet still another object of the present invention is to provide ashielded plugwire for use with an improved shielded plugboard assemblyof a minimum size so as to allow a greater number of such plugwires tobe carried by assembly panels of conventional size than has beenheretofore known in the art.

These and other objects of the present invention will become apparent tothose skilled in the art upon a reading of the following detaileddescription when taken in conjunction with the drawings in which thereis shown and described a preferred embodiment of the invention; however,it is to be understood that this embodiment is not intended to beexhaustive nor limiting of the invention but is given for purposes ofillustration in order that others skilled in the art may fullyunderstand the invention and the `principles thereof and the manner ofapplying it in practical use so that they may modify it in variousforms, each as may be best suited to the conditions of a particular use.

In the drawings:

FIG. l is a perspective, exploded view of one embodiment of a plugboardassembly particularly illustrating the latching assembly and guide meanscontained within the rear bay frame for securing positively the frontpanel frame therein;

FIGS. 2(a) through (e) is a diagramamtic and seque-ntial illustration ofthe closing operation in four different stages of the front and rearframes of one embodiment of the plugboard assembly through one completecrank cycle;

FIG. 3 is a side elevational, sectional and enlarged view of the springcontact member for use in one embodiment of the plugboard assemblyshowing the insertion ofl a barrel support member or insert by a specialtool used to insure positive attachment and support of the contactmember within a panel wall;

FIG. 4 is a perspective and enlarged View of the inserting tool shown inFIG. 3 used to position the barrel support member within the tubularbarrel chamber of the spring contact member;

FIGS. 5(11) through (d) is a diagrammatic sequential portrayal of theclosure of the front and rear frame panels which creates a positivephysical and electrical contact between the plugwise and the springcontact member;

FIG. 6 is a side elevational, fragmentary, sectional and enlarged viewof the rear panel board and the interconnection on its front surface ofa lapped-joint grid arrangement constructed from a plurality ofconductive copper covered strips of an insulating material;

FIG. 7 is a side elevational, sectional, fragmentary view of the rearpanelboard of one embodiment of the plugboard assembly illustrating theattachment of a rear grid to the back surface of the rear panelboard;

FIG. 8 is a perspective, fragmentary view of the grid formed fromconductive strips of material to create isolating cham'bers for assemblyconductors illustrating a securing stud attached thereto which normallyextends through an aperture in the rear panelboard;

FIG. 9 is a side elevational, sectional, fragmentary and slightlyenlarged View of an improved shielded plugwire held within an apertureof a front panelboard of one embodiment of a .plugboard assembly;

FIG. 10 is a side elevational, sectional and fragmentary view of aspring contact member secured within an aperture of the shieldedplugboard assembly rear panel as shown in FIG. illustrating thepositioning of the U-shaped flap within the counterboard portion of theaperture;

FIG. 11 is a side elevational, fragmentary and exploded view of twoconductive strips in their inclined angular relationship forming aportion of the insulating grid shown in FIG. 8;

FIG. 12 is a front elevational, fragmentary and sectional view of a rearpanelboard containing a plurality of spring contact members havingU-shaped supports held within the intersecting recesses etched in theface of that panel;

FIG. 13 is a side elevational, sectional and fragmentary view of thebarrel portion of a spring contact member being held lwithin an apertureof the rear panelboard;

FIG. 14 is a rear elevational view of a rear panelboard showing thebarrel portion of a plurality of spring contact members being securedagainst removal by a diverging U-shaped ap attached thereto;

FIG, l5 is a front eevational view of the rear bay panel sustaining aplurality of spring contact members in contact alignment withinindividual compartments formed lby the grid constructed of a pluralityof lapped-joint conductive strips;

FIG. 16 is a front elevational view of the panel shown in FIG. 15 havingthe spring contact members and grid removed to illustrate thecounterbored apertures which receive the U-shaped legs of the springcontact member barrel portions; and

FIG. 17 is a sectional View taken along lines 17-17 of FIG. 16illustrating the depth of the counterbored apertures.

Referring now to the drawings, a fixed plugboarad panel frame generallydesignated 9 holds a plugboard panel of any suitable electricalinsulating material generally designated 10 in FIG. l which is providedwith rows and columns of apertures 12 adapted to receive therein a setof spring contact members 14. As best shown in FIG. 10, contact Amembers14 are the terminals for the leads which electrically couple the lixedpanel to the sensing elements and the operative instrumentalities of thecomputer or the like (not shown) with which the plugboard assembly isused. Contact members 14 may take any suitable form, but a particularand preferred embodiment best suited for the .present plugboard systemhas been adapted and will be described subsequently in greater detail.

Cooperating with contact members 14 to effect the desired circuitinterconnections within the computer or the like are plugwire connectors16 that are adapted to be received by a plurality of apertures 18 withina front panel Iboard generally designated 20 which is formed of asuitable insulating material and constructed as an integral component ofthe front panel frame generally designated 21.

To permit the front panelboard 20 (hereinafter referred to as panel 20)to be detached from the entire plugboard assembly, rear panelboard 10(hereinafter referred to as panel 10) is securely retained by aplurality of retaining rails 22 each of which form a portion of frame 9and contain a number of contoured recesses 24, 25, and 26 particularlyshaped to mate with and receive cooperatively guide members 28, 30 and32. To attach panel 20 to the rear frame 9 and position that panel in asubstantially parallel relationship with panel 10, guide members 28 aredirected generally into recesses 24 and particularly into the uppernotched indentations 34 which will thus allow panel 20 to be looselypivotable within the rear frame structure, particularly side rails 22 sothat panel 20 is adapted to swing into the face of panel 10 and bejuxtaposed with respect thereto. As panel 20 swings into the face ofpanel 10, guides 30 and 32 are generally received within recesses 25 and26.

The closure operation of panel 20 with respect to panel 10 and thesubsequent latching of these two panels in an interconnectedrelationship is best illustrated in FIGS. 2 (a) through (e). The cammingmechanism generally designated 38 is most clearly illustrated in FIG. 1wherein there is shown a rod 40 rotata'bly maintained by side rails 22forming a portion of rear frame 9. A camming surface 42 is eitherintegrally or separately attached to rod 40 to provide an offset or risewhich will subsequently engage the lower edge 44 of frame 21. A contactpin 46 extends perpendicularly from the longitudinal axis of rod 40 andis positioned particularly to limit the rotational movement of rod 40between prescribed limits. Those limits are controlled by limiting lugs48 and 50 which extend perpendicularly from the interior wall 51 of aside rail 22 and directly engage contact pin 46 upon rotation of rod 40.A crank arm 52 communicates with rod 40 and is positively securedthereto to permit rotation of rod 40 and its related camming surfaces 42upon displacement of crank 52.

In FIG. 2(a), the panel 20 has -been loosely positioned so that guidemember 28 rests in indentation 34, and a -gravity actuated rotation ofpanel thereabout is effected. As panel 20 pivots about guide member 28,it swings into the face of panel 10 and `becomes juxtaposed with respectthereto so that guide members 30 and 32 rest loosely `within recessesand 26. Upon gravity actuated rotation of panel 20 into the face ofpanel 10, the lower edge 44 of front panel 20 rests against the surface54 of ca m 42 as particularly illustrated in FIG. 2(b). Note that crank52 is in a substantially horizontal position so that contact pin 46engages limiting lug 50 thus precluding further displacement of crank 52in a downward direction.

Once panel 20 has been seated in a substantially parallel position withrespect to panel 10, crank 52 can be rotated since this will in turnrevolve rod 20 and slide camming surface 42 against the lower edge 44 ofpanel 2). As the cams highest surface 56 is at a location which wouldcontact edge 44 of panel 20 when crank arm 52 is in a substantiallyvertical position, the gradual displacement of crank 52 toward thevertical position will gradually elevate panel 20 with respect to panel10 and cause the respectively related and carried plug wires and springcontact members to become engaged positively for electrical connection,an operation which will be described in greater detail subsequently.Note in FIG. 2(6) that as panel 20 is elevated, guide members and 32have commenced to enter grooves 58 and 60 extending from recesses 25 and26 which act as guide means to induce selected movement of panel 20 withrespect to panel 10 when crank 52 is displaced. Complete displacement ofcrank 52 to a substantially vertical position as shown in FIG. 2(e)urges panel 20 to a maximum height with respect to panel 10 and wedgesguide means 30 and 32 securely into recesses 58 and 60 so that frames 9and 21 cannot be inadvertently displaced each from the other. Note thatas panel 20 is lifted by the action of camming surface 42 revolving withrod 40, guide member 28 which was used initially to loose- 1y connectand pivot -panel 20 with respect to panel 10 is lifted from recess 34and plays no part in retaining the respective frames in aninterconnected relationship. Only when crank 52 is shifted downwardlyfrom the vertical position to a substantially horizontal position asshown in FIG. 2(a) does guide member 28 again come into play because ofthe gravity actuated displacement of panel 20 downwardly to disengageguides 30 and 32 from recesses 58 and 60.

The physical and electrical connections made between plugwires 16 andspring contact members 14 when a plurality of these components areretained within apertures 12 and 18 of panels 10 and 20 is sequentiallyand diagrammatically illustrated in FIGS. 5 (a) through (d). Thesesequential diagrams are positioned to illustrate particularly the actionof a spring contact member 14 and a plugwire 16 when panel 20 is movedwith respect to panel 10 as shown in FIGS. 2(b) through (e). Forexample, when panel 20 has become substantially parallel with panel 10as shown in FIG. 2(b), the relationship between all spring contactmembers 14 and plugwires 16 are as particularly illustrated in FIG. 5(a) which is situated directly below the panel positioning drawing abovedescribed. As crank 52 is displaced to approximately an incline of 45degrees with the horizontal, panel 20 shifts upwardly as shown in FIG.2(0) and plugwire 16 lifts to engage the lower tip 62 of the contactportion generally designated 64 of member 14. As crank 52 continuestoward the substantially vertical -position it occupies when frame 21 issecurely locked into position with respect to the frame 9, plugwire 16continues to ride upwardly against the narrow contacting surface 66 ofthe contact portion 64 of spring 14. When crank 52 has been secured inthe vertical position as shown in FIG. 2(e), plugwire 16 has slidablymoved against the narrow contact surface 66 of portion 64 to a highposition along that surface where it will be maintained in a securefashion for positive electrical connection. Thus it can be seen thatcontact surface 66 of spring 14 can be made completely dust free andcurrent receptive by one or two cycles or repetitions of operation ofcrank 52 since lifting crank 52 from a horizontal to a vertical positionwill cause plugwire 16 to ride against contact surface 66 from itslowermost point to an upper position thereon and thus wipe and clean themetal surface in a firm manner. When crank 52 is lowered, plugwire 16moves back over the previously wiped surface to a disengaged position asshown in FIG. 5 (a). Any number of such operations can be effected t0insure absolutely clean contact surfaces and troublefree electricalconnections.

When crank arm 52 is moved from the horizontal to the substantiallyvertical position substantially parallel to side rail 22, it isreleasably secured to that rail by means of a ball 68 revolvablypositioned in a housing 70 which in turn is secured to rail 22 by anysuitable means. Crank 52 has on its interior surface 72 a recess 74 forreceiving ball 68 when lever 52 is in an upright position in alignmenttherewith. The securernent of lever 52 avoids an accidental displacementof that lever which might allow panel 20 to become disengaged from panel10.

Plugwire 16 can be of any conventional manufacture, however, bestresults have been achieved when a wire such f as described and disclosedin my pending application Ser.

No. 412,447 is used, this being of a conventional nonshieldedconstruction best suited for ordinary and normal operation. To suitparticular applications and needs, a shielded plugwire has been devisedwhich is suggested for use with the shielded plugboard assemblysubsequently to be described that occupies approximately one-half thesurface area heretofore required when using shielded plug contractors.My shielded plugwire as illustrated in FIG. 9 is comprised of an innerconductor member 76 which has as integrally aiixed contact tip 78extending from the leading or forward end and a suitable shielded wire80 secured to the rearward end of that member. An insulating sleeve 82surrounds conductor member 76 so as to preclude any physical contact orelectrical continuity by another metallic object with that member whileit is surrounded by the sleeve. A grounding shield 84 surroundsconductor member 76 and insulating sleeve 82 and extends rearwardly toconnect with wire shield 83 of conductor 80. A suitable covering 86 ofvinyl or other desirable material encloses the rear portion of groundingshield 84 and the junction of that shield with the grounded or shieldedcover 83 of conductor 80. Shield 84 is particularly constructed with aplurality of extending, resilient, and flexible fingers 87 which lockthe plugwire 16 releasably within aperture 18 of panel 20 and assurethat a uniform system ground is achieved. When plugwire 16 is insertedinto an aperture 18, lingers 87 are pressed inwardly to allow movementof a plugwire into a board aperture. Once seated therein, ridges 89prevent accidental removal of the plugwire from the panel.

Spring contact member 14 is comprised of a barrel portion generallydesignated 90 which is adapted to be received by apertures 12 in panel10 of rear frame 9, and a barrel insert 92 which is received withinbarrel portion 90 secures contact member 14 in a pre-selected positionwithin an aperture 12 in panel 10. FIGS. 3 and 4 illustrate theinjection of barrel insert 92 by means of a tool 94 which is notincluded as a part of the present inventive concept, but which functionsto position inserts 92 when rotated approximately degrees. A leaf-springportion 96 integrally extends from barrel portion 90 and supports acontact portion 64 substantially formed in a V-shaped fashion to providea rib having a narrow contact surface 66 which mates with the contacttip 78 of plugwire 16. The natural resiliency of spring portion 96allows that member to flex as plugwire 16 is moved thereagainst andupwardly as previously described and portrayed in FIGS. 5(a) through(d). A reinforced belly 100 is crimped within spring 14 at the junctionof barrel portion 90 and spring portion 96 to provide additionalstrength between these components and to withstand the numerousmovements of spring 96 with respect to barrel 90 when plugwire 16 iscontinuously urged thereagainst and subsequently removed.

Spring members 14 are secured within apertures 12 of panel 10 in aparticular fashion in order to insure that they will remain in fixed andimmovable when exposed to the continued physical connection ofassociated and interconnecting plugwires 16. The forward end of thebarrel portion 90 generally designated 102 is constructed in a U-shapedmanner so that the legs 104 can be securely imbedded within theplurality of intersecting grooves 106 or on the front surface of panel10, thus precluding any rotational movement of member 14 within aperture12 of panel 10. It has been found advantageous to seat spring members 14in alternate directions (see FIGS. l2 and l5) so as to uniformlydistribute the force exerted by the spring 14 against the contact pin 78of plugwire 16 when panel 20 is urged against panel 10 and the contactmembers 14 and plugwires 16 become interconnected.

The rearward portion 107 of panel 10 is essentially smooth and a secondU-shaped member 108 integral with barrel portion 90 of spring member 14can be expanded in a diverging manner so as to preclude a removal ofmember 14 by inadvertent or accidental pulls or blows.

It is, of course, understood that the assembly previously described iscompletely effective for fuse in unshielded systems when -using aconventional plugwire rather than the shielded or insulated plugwirehereinabove described. As computer technology advances and current andvoltage ratings become more and more critical, it is desirable andessential to avoid any unbalancing characteristics by the use of totallyshielded systems. It has consequently -been found desirable to providethe assembly herein above described with shielding means so as tocompletely isolate individual conductors and establish a uniform andconsistent ground throughout the entire system.

Panel 10 is particularly constructed for use in a shielded system byassembling a plurality of conductive strips such as shown in FIG. 11 anddesignated 110 and 112 which are constructed with a plurality of slots114 so that they might be intermated to form a grid generally designated115 (FIG. 8) having individual compartments 116, each surrounding aconductor assembly such as is shown in FIG. (d) which will besubsequently described. Strips such as those designated 110 and 112 arecovered with a conductive material so that upon intermating with eachother, they become a continuous conductor which may be secured to thesystem ground and provide a uniform neutral or ground potential forcomputer operation. The grid defined by the intermeshing of a number ofconductive strips such as 110 and 112 then forms rows and columns ofcompartments 116 on the front 117 of panel 10 which will house thespring contact members 14 within for subsequent mating with plugwires16. Upon the assembly of a number of conductive strips 110 and 112 toform the grid as shown in FIG, 8, several securing studs generallydesignated 118 which extend through aperture 12 and engage the grid 115at a junction 122 where it is su'bsequently soldered to insure againstseparation and displacement. The X-shaped slots 124 are carried on thegrid-engaging portion generally designated 125 of stud 118 while aflange 126 extends rearwardly of the stud to preclude its inadvertentmovement from aperture 12 of pane 110. A connector 128 can then besecured Within aperture 130 of stud 118 to permit attachment of aconductor or ground wire 132 extending to the system neutral or ground.It has been found advantageous to arrange a pattern of studs 118uniformly throughout selected perforations of panel in order to insure aconsistent ground attachment with the grid formed by conductive stripssuch as designated 110 and 112.

A somewhat thinner grid 136 shown in FIGS. 7 and l5 is formed from aplurality of conductive strips similar to those disclosed in FIGS. 6, 8and ll and designated 110 and 112 in FIG. l5 to cover the rearwardportions 108 of spring members 14 as they extend from the back surface107 of panel 10 for securement to a plurality of conductors (not shown).As this conductor-spring contact member junction is essentially of anonsymmetrical and non-uniform configuration, better results areobtained if these junctions are also shielded within individualcompartments formed from the interconnection of a number of conductivestrips forming a grid. Again, additional grid securing studs generallydesignated 134 extend through aperture 12 of panel 10 as shown in FIG. 7to attach the thinner grid generally designated 136 to the rear side 107of the panel. The height of grid 136 formed of the intermeshingconductive strips on the rear side 107 of panel 10 does not equal theheirght of grid 115 attached to the front surface 117 of panel 10covering the interconnection of plugwires and spring contact members.Since the conductor connection is made closely adjacent the rear surfaceof rear panel 10, the shield formed from the assembled grid 136 need notextend away from surface 107 of panel 10 to any great degree.

-Upon interconnection of front panel 20 with rear panel 10 their carriedcomponents, namely plugwires 16 and spring contact members 14, theassembled grid 115 surrounding the connecting plugwires and contactmembers occupies substantially the majority of space between panels 20and 10'. It has been found advantageous to produce strips such as thosedesignated and 112 from a nonconductive plastic material and then coatthese strips with copper or some other suitably conductive material toprovide the necessary conductivity and to conserve weight and expenseexperienced in the use of conventional solid materials.

It has also been found advantageous to use a conventional compositephenolic for panel 20 and simply to coat this panel uniformly even tothe extent of coating the interior walls of apertures 18 with asimilarly conductive material to provide a uniform system ground orneutral.

While in the foregoing specification and drawings I have shown anddescribed a preferred embodiment of my invention, it will be recognizedby those skilled in the art that many modifications and variations maybe made in the construction and arrangements of the front and rearpanels, the assembled ygrids, the spring contact members and theplugwire connectors as well as other phases of the present inventiveconcept in light of the above teachings `without departing from the realspirit and purpose of this invention. Such modifications of parts andalternatives as well as the use of mechanical and electrical equivalentsto those herein illustrated and described are reasonably included andmodifications are contemplated.

What is claimed is:

1. A multiplecontact interconnecting plugboard assembly for a patchcordsystem comprising: a rear bay with a plurality of apertures and diagonalgrooves intersecting said apertures, said bay carrying a plurality ofspring contact members having leg means resting in said diagonal groovesto non-rotatably secure said spring members therein; a front bay with aplurality of plugwire receiving apertures, said bay being removablypivoted on said rear bay and having a plurality of plugwire membersremovably positioned in said plugwire receiving apertures and adapted toengage said spring contact members upon interconnection of saidassembly, said front bay being adapted to be swingably juxtaposed withsaid rear bay with said plugwire members spaced from said spring contactmembers by a given distance to permit bay closure; camming means movablysecured to said rear bay and operable to urge said front bay upwardly avertical distance greater than said given distance to ca-use saidplugwire members to bear against said spring Contact members and effectcontact therebetween; a crank arm communicating with said camming meansand adapted to pivot between preselected limits, said camming meansbeing responsive to pivotal movement of said arm; guide means carried bysaid rear Ibay to direct said front 'bay upwardly with respect theretofollowing operation of said camming means while maintaniing said rearand front bays at a constant spaced-apart relationship sufficient toallow Contact between said spring contact and plugwire members; andmeans for releasably securing said crank arm upon rotation of saidcamming means to retain said front and rear *bays in said spacedrelationship and maintain said plugwire members in engagement with saidspring contact members.

2. A multiple-contact interconnecting plugboard assembly as set forth inclaim 1, said camming means including a control rod rotatably maintainedby said rear bay having (a) dual camming surfaces formed thereon, aContact Ipin extending perpendicularly from the longitudinal axis ofsaid rod adjacent one side of said rear bay and rst and second limitinglugs secured to one side of said rear bay and positioned to restrictrotation of said rod camming surface between limits by said first luigengaging said contact pin when said plugwire members are spaced fromsaid pin members -by a given distance upon juxtaposition of said baysand said second lug engaging said contact pin when said front bay isurged up wardly and said plugwire members have moved to engage saidspring members and effect contact therebetween.

3. A multiple-contact interconnecting plugboard assembly for a patchcordsystem as set forth in claim 1, said guide means including threerecesses on each side of said rear bay and (a) three complementing lugsprojecting from each side of said front bay to mate within said recessesand induce preselected pivotal and slidable movement of said front baywith respect to said rear bay upon operation of said camming means, saidrecesses and complementing lugs precluding disengagement of saidplugwire members with said spring members until said camming meansallows movement by said guide means of said front bay downwardly withrespect to said rear bay to disengage said members.

4. A multiple-contact interconnecting plugboard assembly for a patchcordsystem as set forth in claim 2, said guide means including threerecesses on each side of said rear bay and (a) three complementing lugsprojecting from each side of said front bay to mate within said recessand induce preselected pivotal and slidable movement of said front baywith respect to said rear bay upon operation of said camming means, saidrecesses and complementing lulgs precluding disengagement of saidplugwire members with said spring members until said camming meansallows movement by said guide means of said front bay downwardly withrespect to said rear bay to disengage said members.

5. A multiple-interconnecting plugboard assembly for a patchcord systemas set forth in claim 1, each of said spring contact members comprisinga |barrel portion having a detent and adapted to Ibe received by one ofsaid rear bay apertures for mounting said member on said plugboard, aleaf sprinig portion integrally extending from said barrel portion, acontact portion integral with said spring portion forming a rib toIprovide a narrow contact surface, and a barrel insert having acircumferential recess, said insert extending within said lbarrelportion to support and secure said spring contact member in apreselected position on said rear bay.

6. A multiple-interconnecting plugboard assembly for a patchcord systemas set forth in claim 4, each of said spring contact members comprisinga barrel portion having a detent and adapted to be received by one ofsaid rear bay apertures for mounting said member on said plugboard, aleaf spring portion integrally extending from said barrel portion, acontact portion integral with said spring portion forming a rib toprovide a narrow contact surface, and a barrel insert having acircumferential recess, said insert extending within said barrel portionto support and secure said spring contact member in a preselectedposition on said rear bay.

7. A multiple-contact interconnecting plugboard assembly for a patchcordsystem as set forth in claim 1, said rear bay being of an insulatingmaterial and carrying a plurality of grounded conductive stripsassembled in the form of a grid to form individual compartmentssurrounding and shielding said spring members.

8. A multiple-contact interconnecting plugboard assembly for a patchcordsystem as set forth in claim 6, said rear bay being of an insulatingmaterial and carrying a plurality of grounded conductive stripsassembled in the form of a grid to form individual compartmentssurrounding and shielding said spring members.

9. A multiple-contact interconnecting plugboard assembly fora patchcordsystem according to claim 7, said front bay having a conductive.grounded surface coating uniformly distributed thereover.

10. A multiple-contact interconnecting plugboard assembly for apatchcord system according to claim 8, said front bay having aconductive grounded surface coating uniformly distributed thereover.

11. A multiple-contact interconnecting plugboard assembly for apatchcord system according to claim 9, each of said plugwires having aninner conductor member, an insulating sleeve surrounding said conductormember and adapted to insulate inner conductor member from said frontbay conductive coatinig, and a grounding shield substantially envelopingsaid sleeve and conductor mem- Iber to position shield and ground saidplugwire with respect to said front bay conductive surface.

12. A multiple-contact interconnecting plugboard assembly for apatchcord system according to claim 10', each of said plugwires havingan inner conductor member, an insulating sleeve surrounding saidconductor member and adapted to insulate inner conductor member fromsaid front conductive coating, and a grounding shield substantiallyenvelop-ing said sleeve and conductor member to position shield and:ground said plugwire with respect to said front bay conductive surface.

References Cited UNITED STATES PATENTS 2,802,189 8/1957 Bishop et al.339-18 2,975,395 3/1961 Sitz 339-18 XR 2,983,895 5/1961 Pasi-k 339-217XR 3,052,749 9/ 1962 Snapp et al. 174-685 3,102,768 9/1963 Schwamb339-217 3,231,663 1/1966 Schwartz 174-35 3,246,208 4/1966 Lex et al339-18 XR 3,264,526 8/ 1966 Wiggerman 317-101 3,288,957 11/1966 Fraley339-18 XR 3,303,454 2/1967 Crowley et al 339-18 3,323,095 5/1967 Bush etal. 339-18 FOREIGN PATENTS 487,606 12/ 1929 Germany. 750,244 6/ 1956Great Britain.

MARVIN A. CHAMPION, Primary Examiner.

PATRICK A. CLIFFORD, Assistant Examiner.

U.S. Cl. X.R. 339-143, 258

